The following U.S. Patents are hereby incorporated herein by reference in entirety.
U.S. Pat. No. 7,585,196 discloses a cooling system for a marine propulsion device that provides a transom opening that is sufficiently low with respect to other components of the marine propulsion device to allow automatic draining of all cooling water from the system when the marine vessel is removed from the body of water in which it had been operating. The engine cooling passages and other conduits and passages of the cooling system are all located at positions above the transom opening. The system provides automatic draining for a marine cooling system that is an open system and which contains no closed cooling portions.
U.S. Pat. No. 7,476,135 discloses a cooling system for a marine vessel that is configured to allow all cooling water to flow out of the cooling circuit naturally and under the influence of gravity when the marine vessel is removed from the body of water. All conduits of the cooling circuit are sloped downwardly and rearwardly from within the marine vessel to an opening through its transom. Traps are avoided so that residual water is not retained within locations of the cooling system after the natural draining process is complete. The opening through the transom of the marine vessel is at or below all conduits of the cooling system in order to facilitate the natural draining of the cooling system under the influence of gravity and without the need for operator intervention.
U.S. Pat. No. 6,808,432 discloses a cooling system for an out drive of a stern drive device that draws water from a body of water in which a marine vessel is operated and conducts the water through a conduit to an outlet end that is configured to direct a stream of water into a space which is defined under a removably attachable cover and above a surface of a heat producing portion of the out drive. The cover contains a turbulently flowing stream of water in the space in order to more efficiently conduct the water in thermal communication with the outer surface of the heat producing portion. Return passages are provided between the cover and the surface of the out drive to allow water to return, under the influence of gravity, back to the body of water from which it was drawn.
U.S. Pat. No. 6,571,753 discloses an engine coolant draining system that is provided with a vent module that is shaped to be inserted into the coolant conduit of a marine engine. The vent module comprises an umbrella-shaped valve which operates as an unidirectional valve to allow air to flow into the coolant conduit from the region external to the coolant conduit, but prevents liquid from flowing out of the coolant conduit through the vent module when the pressure within the coolant conduit is greater than atmospheric pressure external to the vent module.
U.S. Pat. No. 4,764,135 discloses a marine stern drive unit in which oil is circulated upwardly from the propeller housing and through the drive shaft sleeve to the upper gear case. A return oil line connects from the upper gear case and downwardly through the lower gear case to the propeller housing. The return line is disposed within a cooling water chamber communicating with the drive engine to create an intercooling or heat exchanging effect whereby the incoming water from a lake cools the recirculating stern drive unit lubricant. A combination of threaded drive shaft and internally grooved sleeve is utilized to pump the oil through the system.